St. Ignatius, Montana, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
These conditions suit cabbage, blackberry, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in St. Ignatius, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single St. Ignatius lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around St. Ignatius — soil, climate, flood, and parcel records. How we handle your address.
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St. Ignatius — the short answer
St. Ignatius, Montana: USDA zone 6a, about 174 days between hard freezes, across 341 acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 22
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~174
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 341 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 6a is St. Ignatius's average, not your lot's — a low corner or a tree line moves it. Against St. Ignatius's 174-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in St. Ignatius
Each reading below is measured for St. Ignatius itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSt. Ignatius runs about 174 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSt. Ignatius sits in USDA hardiness zone 6a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country St. Ignatius is in
St. Ignatius sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at St. Ignatius's own centroid rather than borrowed from Lake County.
What Grows in St. Ignatius
Every plant below cleared St. Ignatius's own zone 6a and its 174-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in St. Ignatius?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 25; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 22 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 13 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near St. Ignatius
Closest first, within ~10 miles of St. Ignatius. Listing isn't leaking, and distance isn't exposure.
- STUARTS SERVICE CENTER INC MAIN STUnderground Storage Tanks · 400 ft
- MELVIN NELSON SAINT IGNATIUSUnderground Storage Tanks · 450 ft
- MAE NAFFZIGERUnderground Storage Tanks · 650 ft
- STUARTS SERVICE CENTER INCUnderground Storage Tanks · 1600 ft
- 18N20W14DBD 02Nitrate · 2100 ft
- FLATHEAD HEALTH CENTERUnderground Storage Tanks · 2100 ft
- ALLARDS GENERAL STOREUnderground Storage Tanks · 2200 ft
- STARVIN MARVINSUnderground Storage Tanks · 0.7 mi
- YOUR CHOICE VIDEOUnderground Storage Tanks · 1.1 mi
- 18N20W23DADA01Nitrate · 1.1 mi
- 18N20W10ADD 01Nitrate · 1.6 mi
- FRONTIER POSTS LLCBrownfields · 3.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from St. Ignatius's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near St. Ignatius.
Total Sites
67
within ~10 miles of St. Ignatius
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of St. Ignatius
Severity Distribution
within ~10 miles of St. Ignatius
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around St. Ignatius, Nitrate runs higher than the national average — 40 sites within ~10 miles of St. Ignatius. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in St. Ignatius
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the St. Ignatius average
Your land is one point inside St. Ignatius
Everything above resolves to St. Ignatius as a whole — one PHZM band and one 28°F frost record, read across 341 acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the St. Ignatius Average
St. Ignatius Average
- ●USDA Zones 6a, averaged across St. Ignatius
- ●One soil character for all of St. Ignatius
- ●Frost dates read at St. Ignatius's scale: Apr 22 to Oct 13
YOUR Parcel
- ✓Your exact zone, not St. Ignatius's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in St. Ignatius
Pull a site-specific report for your exact address in St. Ignatius, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that St. Ignatius averages can't show:
We read public map data around St. Ignatius — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the St. Ignatius average
How we know this about St. Ignatius
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at St. Ignatius’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about St. Ignatius
When does frost risk typically end in St. Ignatius?
The last hard freeze (28°F) in St. Ignatius typically lands around Apr 22, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 13.
When is the first frost in St. Ignatius?
The first hard freeze (28°F) in St. Ignatius typically arrives around Oct 13, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 29, so the watching starts about Sep 13 — about 174 days after the spring freeze cleared.
How long is the growing season in St. Ignatius?
Measured between 28°F hard freezes, St. Ignatius sees about 174 frost-free days — roughly Apr 22 through Oct 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 13 to Sep 29, about 139 days.
Is the soil safe to grow vegetables in St. Ignatius?
The federal record around St. Ignatius is a meaningful one — 67 documented sites, mostly Nitrate entries (40), the nearest Underground Storage Tanks record under a tenth of a mile out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in St. Ignatius?
From about Sep 13 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 13 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 13. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at St. Ignatius's scale — its 6a band and its 174-day season. Your yard writes its own version of St. Ignatius's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at St. Ignatius’s own scale
6 of the readings below were taken at St. Ignatius's own scale — its own ~174-day season between 28°F freezes, the 341 acres it covers and 67 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- St. Ignatius's own USDA hardiness band, zones 6aUSDA PHZM 2023
- St. Ignatius's own 28°F hard-freeze dates, about Apr 22 and Oct 13 and the ~174-day span between themNOAA 1991–2020 Climate Normals
- 67 documented contamination sites on the federal record near St. Ignatius, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- St. Ignatius's boundary and the 341 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~174-day seasonGrowable Ground crop-matching engine
- The ecoregion at St. Ignatius's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so St. Ignatius's 341 acres read through its county's SSURGO summaryfrom Lake County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lake County
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Lake County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among St. Ignatius's 341 acreswhy one lot differs from the next →
- Which side of St. Ignatius you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 341 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any St. Ignatius-wide figureread your own land →
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